Programmer for chromatography



Aug. .2

Filed June 20, 1958 7, 1963 1.. B. ROOF PROGRAMMER FOR CHROMATOGRAI HY 5Sheets-Sheet l CYCLE TIME 360OF CAM TRAVEL a a b o=GATE OPEN s lm sl eGATE GATE GATE 1=GATE CLOSED c cl '0 (:1 0 c1 I TIME FIG. 2

g ,l L INVENTOR. a c r I L.B. ROOF a: d BY CHART LENGTH A 7' TORNE V5Aug. 27, 1963 L. B. ROOF 3,101,606

PROGRAMMER FOR CHROMATOGRAPHY Filed June 20, 1958 5 Sheets-Sheet 2INVENTOR. L. B. ROOF HLMJM Aug. 27, 1963 L. B. ROOF 3,101,606

PROGRAMMER FOR CHROMATOGRAPHY Filed June 20, 1958 5 Sheets-Sheet 5 I28OR I30 Nil/I12 IBOAEEIEEI DC 220Q1 Q9; 220/ FIG 7 INVENTOR. L.B. ROOF AT ORNE S Aug. 27, 1963 B. ROOF 3,101,606

PROGRAMMER FOR CHROMATOGRAPHY Filed June 20, 1958 5 Sheets-Sheet 5United States Patent 3,101,606 PROGRAMMER FUR CHROMATOGRAPHY Lewis B.Roof, Bartlesville, Okla, assignor to Phillips Petroleum Company, acorporation of Delaware Filed June 2%, 1958, Ser. No. 743,330 11 Claims.(Cl. 73-23) This invention relates to a programming switch. In onespecific aspect it relates to an improved programmer for use with avapor phase chromatographic analyzer.

In vapor phase chromatography a measured sample is placed in a packedcolumn. This sample is then eluted from the column by passing a carriergas, such as helium, therethrough. The various gases that make up thesample will the eluted from the column by the carrier gas a fixed order.Each of these gases has a different heat transfer characteristic andthis phenomenon is used to determine which of the several gases is beingeluted at a given time. When suitable measuring and control apparatus isassociated with the packed column, a series of curves will be generatedby a given sample of gas during its elution from the column. Thesecurves consist of a series of peaks with each peak indicating a certaincomponent, or in certain cases, two components. It is frequently desiredto select only one or perhaps several, but not all, [of the peaks forrecording or control purposes.

A properly designed timing mechanism can program the events to permitthis to take place. Programming is possible because with a given columnand a given size of sample the substances in the sample will be elutedfrom the column in a known order covering, respectively, predeterminedperiods of time.

Occasionally the peaks generated on elution are quite close togetherwhen plotted on a time axis and the pro-- grammer must be capable ofoperating at a high speed in order to separate the two peaks. Frequentlyin chemical plant operation, especially where hydrocarbons are beinganalyzed, the danger of explosion is great and programming switches aswell as other apparatus must be fire or explosion proof. Also, at timesit is considered desirable to record the results of chromatographicanalyses in a bar graph iiorrn by intermittently operating the recorderchart motor. Also, it is necessary to operate valves for sampling andfor the carrier gas.

In present day chemical plant practice it is common to alter the plantoperation to either accommodate substantially different feedstock or toproduce different products. Sometimes the products, while having themajor component the same, may have strict limitations on certainimpurities therein to satisfy specifications. In order that such a plantbe flexible, its entire analyzing and control system must, of course, beadjustable to the changes in [feed stock or in product. This means, ofcourse, that if an analyzer such as described above is used that it andthe timing mechanism therefior must be adjustalble to conform to the newconditions that are being measured. This is necessary [because differentcomponents may be measured or the elution times and occurrences thereofmay change upon new components appearing in the feed stock.

The instant invention comprises a timing switch which is suitable forconnecting a measuring apparatus such as a Wheatstone bridge to arecorder at selected time intervals. These selected intervals aredetermined by the times at which elution peaks or curves will occur, andthe programmer in its operation, will then permit the recording of onlyselected peaks, but not necessarily of all peaks. Furthermore, therecorder can be operated by the programmer of the instant invention toproduce Bddlfidli Patented Aug. 27, I963 analyses of compositions in a[bar graph rather than in a peak or curve form. The programmer also hassuitable mechanism for rendering it readily adjustable to accommodatechanges in feed stock or in specifications of the product. High speedoperation is achieved by providing one mechanism to electrically connectthe Wheatstone bridge to a recorder and a separate mechanism to breaksuch connection. The adjusting means provided are suitable for holdingthe adjusted portions of the apparatus in position.

Accordingly, it is an object or this invention to provide a programmercapable of higher speed operation than prior art devices. Another objectof this invention is to provide a programmer having means therein toradjusting the timing. It is still another object of the instantinvention to provide a programmer which is explosion proof and hence issuitable for use inchemical plants. Finally, it is an object of thisinvention to provide a programmer which is suitable for use with achromatographic analyzer and which permits selecting which of varioussignals are to be recorded or otherwise used as for control purposes.Other objects and advantages will become apparent from the followingdisclosure.

In the drawings:

FIGURE 1 demonstrates the position of a progr mer when used in achromatographic analyzer circuit;

FIGURE 2 represents the time sequence of events when peaks are generatedon a continuously moving chart;

FIGURE 3 represents bar graphs produced by an intermittently movingchart;

FIGURE 4 is an exploded view of the programmer mechanism;

FIGURE 5 is a cross-section of the cam adjusting mechanism;

FIGURE '6 is a plan view or the assembled programmer of FIGURE 4;

FIGURE 7 is a cross-section through 77 of FIG- URE 6;

FIGURE '8 is a wiring diagram for the delay relay feature;

FIGURES 9-13 are schematic diagrams demonstrating the cooperation of theprogrammer elements.

Referring now to FIGURE 1 there is shown a conventional cfractionatingcolumn 10 having an overhead product line 12 leading through a condenser'14 and a condenser by-pass line 16 to an accumulator 1-8. A reflux line20 returns a proportion the liquid from the accumulator to the column. Aliquid overhead product line 22 delivers the product for storage orfurther processing. The pumps, valves, and their associated controlshave been eliminated in this sketch for clarity.

A sample line 24, having a sampling valve 26 disposed therein, isconnected to a chromatographic column 28. The column is supplied withcarrier gas through a line or conduit 30. The eluted gas from the columnpasses to a sample cell 32 in which is disposed a thermistor S4. Thethermistor 34 comprises a branch of the Wheatstone bridge 36. The bridgeis connected through leads 38 and 42 to a recorder 40.

The lead '42 is connected through a series of parallel switch circuitsto the recorder 49. As shown in the drawing, the switches 220a, c, d, e,and f are those in parallel. The latter four of the switches haveattenuator pots 440, d, e, and f disposed in their circuits. A switch22Gb provides power from source 49 to operate the sampling valve 26responsive to actuation by the program'mer. The switches are associatedwith a delay relay circuit 50 which is likewise operated by theprogrammer to operate the chart motor sequentially to proi cut out ofthe flange.

next to each other.

I) duce bar graphs as will hereinafter be described. The structure ofthese switches is discussed below with respect to FIGURE 9. The detailof the delay relay, which in actuality is built into the programmer 46,will be hereinafter discussed with respect to FIGURE 8.

. Referring nowto FIGURE 2, there is shown a series of'peaks such as is.generated on a continuously operating (recorder when the connectionbetween the bridge and recorder is continuous. A complete cycle ofevents is shown in FIGURE 2: this cycle comprises zeroing the Wheatstonebridge, taking a measured sample of the gas to be analyzed, andselectively recording the peaks and operating the chart motor uponcutting off of the peak.

In FIGURES 2 and 3 the peaks numbered 0, d, e, and correspond to thosewhich may be selectively passed by the switches having the samealphabetical numbers in FIGURE 1. FIGURE 3 demonstrates the resultsobtained when the timer is adjusted to pass only three of these peaks.The term gate as used in FIG- URE 2 denotes the time during which a peakmay be read. When the gate opens, one of the switches 220 is closed;when the gate cl oses, switches 220 are (open, i.e.,

in the position shown in FIGURE 1. As will be hereinafter described, thesignal is passed by making a contact, recording the peak and thenbreaking a contact. FIGURE 3 represents the bar graph which would beproduced by adjusting the programmer 46 to pass only the peaks c, d, andf and to intermittently operate the chart motor in the recorder.

Referring now to FIGURE 4, there is shown a hearing block 100 havingmounted therein bearings 102 and 104. 102 is preferably a journalbearing while 104 is preferably a roller, needle or ball hearing. In thebearing W2 is mounted a shaft 106. This shaft has a timing gear 108mounted thereon and also has mounted thereon a plurality of flangeddetent cams 110* with a portion 111 At the other end of the shaft 1116from the bearing 102 is disposed another bearing in the block 112. Thedetent cam and the timing gear are each held in place by set screws onthe shaft 106. The collar 114 is disposed on the opposite side of theblock 1011 from the timing gear and is fixed to the shaft 106 by a setscrew in order to retain the shaft in position longitudinally.

In the bearing 104 is mounted a cam shaft 116 having a flatted surface118 on whch is mounted a splined coupling 120 (as best seen in FIGURE6). A washer 122 serves tospace the coupling from the back side of thehearing or pillow block. Another flatted surface 124 is provided on theshaft for receiving a timing gear 126. The timing gear and the couplingare held in place by set screws. A washer 125 serves to separate thefront edge of the bearing 104 from the timing gear 126. Disposed next tothe timing gear on the cam shaft is a spring 127 for holding the variousdiscs hereinafter described in position These discs are not fixed to thecam shaft by set screws or the like, 'but rely on the frictionalengagement provided by the spring to keep them position allyrelated onthe shaft. Disposed along the shaft 116 between the spring 127 and theoutboard end of the shaft are a plurality of pairs of cams 123 and 130.The pairs are denoted by the letters a through 1, respectively. Witheach cam is associated a mounting disc 13 2 which is used to connect thecam to the cam shaft in such a manner that timing adjustments can bemade, as will be hereinafter described with respect to FIGURE 5. Each ofthese mounting discs has a hole 134 therein for receiving the shaft 116and also has a plurality of holes 136 corresponding to the total numberof cams 12S and 130.

As shown in FIGURE 5, each and every cam 128, 1 30 has pressed thereintoa bushing 138 having along the internal periphery a series of gear teeth140. In order that each cam beindependently adjustable relative to allother cams, a pinion 142 may be provided for each internal gear 14d andis mounted on a shaft 144 which passes through the holes 136 in themanner shown in FIGURE 5. Alternatively, only one of the paired cams128, 136 need have a pinion 14 2, if complete independent adjustabilitycan be sacrificed. The ends of the respective shafts 142 are fitted withmeans for. manually rotating them, such as screwdriver slots 146. Knobscould also be used, but the design shown is more compact. Figure 4 showsthe exploded view of the pinion and shaft arrangement for one-half thecams, the remainder being omitted for. sake of clarity.

At the outboard end of the shaft 116 is mounted a disc 148 fashionedsimilarly to the mounting discs 132. However, this disc differs in thatit has a collar 151} thereon which passes through a face plate 152 (forcarrying in dicia, is desired). Outboard of 152, but disposed along theshaft and preferably disposed on the collar 150, may be mounted indexmarkers 156 to cooperate with indicia marked on'the member 152. A disc158, having a hole 160, designed to receive the collar 162 on the disc148 is mounted outboard of the index markers 156. A spring 164 biasesthe disc 158 up against the mounting member 152. The spring iscompressed by a bolt 166 which screws into a threaded end of the shaft168. The indicia, face plate, and elements cooperating therewith couldbe omitted, if desired, as long as bolt 166 or other longitudinalpositioning means are provided.

A shaft 181 is fixed in the block 101) at one end and rests on a block184 at the other end thereof. A spacer 136, having a spring collar 188thereon, fits on one end of the shaft to separate the lever mechanismhereinafter discussed from the bearing block and timing gears. A spring190a is mounted on the collar 188. The spring has arms 192 and 194'whichare compressed between the base plate, not shown, and the pin 196a whichis mounted on a lever 19301 that is rotatably mounted on the shaft 180.The lever 198a has a cam follower surface 2611a that engages the camsurface on the cam 128a. Adjacent the lever 198a on the shaft is anotherlever 202a having a magnet 204a mounted at one end thereof. At theopposite end is a cam follower surface 206a which engages the cam 128a.Between the fulcrum provided by the shaft and the magnet is disposed anotch 268a in which the pin 196a may fit. The same assembly is repeatedin like elements b through 1 for a plurality of times continuing downthe shaft to the block 184-. There are right and left hand assemblies ofthe levers 198 and 2112. The operation of these will be explainedthereinafter with respect to FIGURES 9 through 13. The other springs 190are mounted on collars 210. These collars also serve to space the pairsof levers. Although not shown (for the sake of clarity) on allembodiments of the lever 20-2,, each of them has a detent finger 212with a surface 214 for engaging the detent cams which are describedbelow with respect to FIGURE 13.

Referring now to FIGURE 5, there is shown in crosssection the manner inwhich the cams 128 and are mounted to the shaft 116 in such a mannerthat they can be rotated with respect to both the shaft and each otherfor purposes of adjusting the gate, i.e., the length of time that themagnet 204 will be in operative condition as shown in FIGURE 10, or foradjusting to the position of FIGURE 12 to prevent passing of a signal.In essence, FIGURE 5 shows the mounting disc 132 to be in engagementwith the shaft 116 and that the cam discs 129m 130 are supported fromthe mounting disc 132. Of course, if desired, the mounting disc 132could be keyed to the shaft 116 to prevent slippage with respectthereto. A key, square shaft, or set screw could all be considered asequivalent for this purpose. Because of the low torque involved in thissystem it has not been found necessary to do this, friction aided by thebiasing forces of springs 128 and 164 being suflicient to hold the partsin position. As shown in FIGURE 5, the cam 128 (or 1311, as the case maybe) has a bushing 138 pressfitted thereinto with a shoulder 137 thereon.This shoulder engages the internal portion of a flange 133 that is partof the mounting disc 132. When the parts are properly assembled, theshoulder does engage the flange and the pinion 142 meshes with the gearteeth 140'. Other shafts 144 pass through the disc and through theaperture provided by the bushing 130. When adjustment of the timing isdesired a screw driver can be inserted in the slot 146 to turn the shaft144 and thereby to rotate the cam 128 or 13 2 in the flange 1'33 andwith respect to the shaft. Although the pinions 142 aid in holding thecams in their respective adjusted positions, the aforementionedfrictional engagement has been found sufiicient to do so. Hence, onlyone pinion need be provided for each pair of cams, if desired.

Variations in this structure would include mounting one of the. cam.discs 128 or 130 without the bushing 138 therein. This would require, ofcourse, either fixing the cam disc to the shaft by a spider or providinga central structure analogous to that of the mounting disc 132. Anothervariation would be to make mounting disc 182 integral with one of thecams. Both of these variations then require only one pinion 142 and onlyone shafit 144, but are permissible only when some sacrifice inindependent adjustability of the cams is permissible. The end result ofall these structures is to permit one cam to be moved relative to theother and to the shaft without having to disassemble the entire camshaft. The advantage to the illustrated structure is that the cam discsmay all be of like structure, hence be interchangeable, as may be themounting discs.

Referring now to FIGURE 6-, there is shown an assembly of the mechanismillustrated in FIGURE 4. The part numbers are the same. It may readilybe seen that the construction provides a compact and rugged unit. FIGURE6 also shows a synchronousmotor 240 having on its drive shaft a splinedcoupling 242 which engages the coupling 120 to provide a constant speedto the cams that are mounted on the shaft 116. It should also be notedthat the diameter of the timing gear 100 is four times that of thetiming gear 126 in order that the detent cams operate only once out ofevery four revolutions. In accordance with this design it is necessarythat the cutout portion 111 on the detent cams be 90 degrees. Of course,different ratios and cutouts can be made according to the ratio ofoperation desired. It should also be noticed that the shaft 106 ispositioned for longitudinal movement as well as rotary'movement in thebearing 102. This permits engaging and disengaging the detent fingers212 by merely pushing the shaft 106 toward the rear. .TWo shafts 106 areshown in order that detent cams may be provided to all cams, both theleft and righthand pairs.

The motor 240 acts as a counter-weight about the hearing 104 and servesto balance the effect of the cams and other mechanism on the other sideof the bearing. This permits a cantilever construction going from thebearing 104 to the outboard end of the shaft 116 and eliminates thenecessity for an outboard bearing.

FIGURE 7 is a section through 77 of FIGURE 6. FIGURE 7 illustrates thecooperative positions of the detent finger 214 and the detent cam 110.It also illustrates the position in the programmer of the reed switches220 which are described in greater detail below in reference to FIGURE9. These reed switches are placed in cradles 245 which are in turnmounted on a base 246. In the switches shown there are two reed switchesactuated by each magnet. One of these is for carrying direct current(D.-C.) in the circuit shown in FIGURE 1; the other is for carryingalternating current (A.C.) in the circuit shown in FIGURE 2. A shield244 is interposed between them to prevent the AC. from effecting the DC.The pairs of switches are both simultaneously actuated when theirrespective magnets 204 fall down into actuating position as shown inFIGURE 7. These switches may be the Revere Glaswitch described inEngineering, Bulletin No. 1057, by Revere Corporation of America,Wallingford, Connecticut, or their equivalent.

The details of the delay relay for the chart motor are shown in FIGURE8. The power source 49 (FIGURE 1) is connected through lead 52 to arecorder chart motor which is part of the recorder 40. Another lead 54connects the other side of the source 49 to the parallel circuits, eachcontaining one of the switches 220a, c, d, e, and j". The a switch (forzeroing) is connected by a lead 56 to switch 58. The switch 58 is adouble throw switch having the contacts 60 and 61. The contact 60 isconnected by a lead 63 to a switch 65. The switch 65 is connected by alead 66 to the recording chart motor. The switches 0 through f areconnected by a lead 68 to a solenoid 70 which actuates the switch 58.The other side of 70' is connected to the lead 52. The contact 61 isconnected through a delay relay solenoid 72 to the lead 52. This may bea thermal delay switch, such as the Amperite Thermostatic Delay Relaysold by Amperite Company, Inc, 56 Broadway, New York 12, New York.

Referring now to FIGURE 9, there is shown schematically the mechanism ofthe elements mounted on the shafts 106, 116, and 180. In addition, thereis shown the structure a preferred type of magnetic switch 220, which isused for the switches of FIGURES 1 and 2. In this switch there are twoflexible magnetic elements224 which close their contacts 226 whensubjected to a magnetic field as from a magnet 204. These contacts areenclosed in a sealed container 222. One, two or more of these switchescan be actuated by the magnet 204 when it is moved into proximity tothem.

The ope-ration of the programmer in conjunction with a system such asshown in FIGURE 1 will now be explained by referring to FIGURES 913. Themotor 240 is started and operated at synch-onous speed driving the camson shaft 116. As shown in FIGURE 2, the first operation necessary in acycle is to zero the Wheatstone bridge 36 to correct for any drift thatmay have occurred due to aging of the thermistor or other measuringelement 32.

FIGURE 9 shows the position of the elements before any of the switchesclose to permit a signal to pass between the bridge and the recorder asshown in FIGURE 1. For the sake of clarity the cams 128 and 132 areshown on separate shafts. The synchronous motor drives the shaft 116 andbrings the cam 130 to a position such that the cam follower surface 206of the member 202 moves upward sharply to the position shown in FIGURE10. This is because the magnet 204 comprises a weight at the oppositeend of the lever and gravity causes the opposite end to drop. When thelever assumes the position shown in FIGURE 10 the pin 106 is then in anoperative position with respect to the lever 202, but is prevented fromoperating by the cam 128 which acts against the bias of spring 100. Inorder for the lever to drop, as aforesaid, the detent cam 110 mustrotate to the position shown in FIGURE 10 so that the flange cutout 111permits the finger 214 to fall free of the cam permitting the downwardmovement of the right end of lever 202. I

The cams and 128 are positioned on shaft 116 with respect to each otherso that the lever 202 will retain the position shown in FIGURE 10 for apredetermined period of time. When the lever 202 has dropped, thecontacts 226 of the switch close to thereby open the gate as discussedwith respect to FIGURE 2. The next event is closing the gate, i.e.,breaking this contact.

To close the gate, the cam 128 moves'to the position shown in FIGURE 11,whereupon the pin 196 moves sharply upward under the bias of spring 190,carrying with it the lever 202. This also returns the finger 214 to aposition where it can be again engaged by the flange of detent cam 110.This upward movement causes the contacts 226 to open by removing themfrom the field of magnet 204.

i as described in FIGURES 9 through 11.

When the above events have taken place on the a cam and lever group, thebridge is zeroed. The next event is to operate the sample valve 26 by alike sequence on'the b group. The peaks are then read by causing the c,d, e, and 1 groups operate, respectively, intheir proper sequence. Theentire cycle is then repeated.

Where it is desired to produce a bar graph (FIGURE 3) instead of peaks(FIGURE 2) it is necessary to intermittently operate the recorder chartmotor by means such as the delay circuit of FIGURE 8. The operation ofthis circuit follows: I

Simultaneously with the actuation of the switches 220s through f inFIGURE 1 (i.e., the pea recording switches), an alternating current isapplied to the recorder chart motor by the circuit of FIGURE 8. Theswitches in FIGURE 8 are those denoted in FIGURE 7 as 22%. Using theswitch number 2200 of FIGURE 8 as an example, it is closed when a magnetmoves to the position of FIGURE 10 and current is admitted through asolenoid 70 which closes the contact at 61 admitting current to thedelay relay solenoid 72. For a portion of the time that the signal isbeing sent from the bridge to the recorder, the switch 65 remains open,but upon heating of the solenoid 72 by the current therethrough thisswitch 65 closes. This has no effect on the recorder chart motor at thistime because the switch 58 is not in contact with 60. However, thiscontact is made upon the cam 130 moving the magnet away from the reedswitch 220 and thereby causing the contact to be broken at 61 and to bemade at 60. This then admits current to the recorder chart motor unitsuch time as the delay relay 72 opens the switch 65. The effect of thisstructure is to permit the recorder chart motor to operate immediatelyupon the closing of the gate as shown in FIGURE 3. A short period oftime after the chart motor stops (in the preferred embodiment being 2 /2degrees of cam shaft rotation when the chart speed is 60 inches perhour) the circuit is ready for the next peak which is recorded in thesame manner as described above with respect to the 1 peak lettered 0.Subsequent operations merely repeat the operation of the respectivelevers 202 and 198 (d through 7) by their respective cam-s 128 and 130.

FIGURE 12 shows how the relative positions cams 128 and 130 whenadjusted with respect to each other so that a particular signal will notpass between the bridge and the recorder. For example, this could bedone to cut out peak e by adjusting cams 128a and 1321:. What is done inFIGURE 12 is to adjust the relative positions of the cams by turning aproper one of the shafts 146 (there being but one shaft for the pair ofcams 128e and 132a) to cause one of the cams to rotate relative to theother. When properly positioned the cam 128e is then positioned so thatit will move the pin 1%:2 into engagement with lever Zll-Ze before theearn 130:: can actuate the lever. This, of course, prevents the leverfrom dropping and from actuating the switch 220. In the cycle shown inFIGURE 2, this adjustment would be made on the e group.

FIGURE '13 shows how the detent cam operates to prevent the lever 202from actuating the switch 220 when it drops. It must be remembered thatthe detent cams 110 turn at only a fraction of the speed of cams 134iand 128, for example, at one-fourth of the speed. This, in turn, meansthat only one time out of every four will the switch 220 be actuatedand, insofar as the recorded signal is concerned, it means that only onesample out of every four will have a particular component registered onthe recorder. As shown in FIGURE 11, the detent cam engages the finger214 so that when cam 130 moves to the operating position for the lever202 the magnet 2M cannot drop. It should be noted in this feature thatthe relative positions of the cams can remain the same as is necessaryto provide proper timed and programmed switch actuation However, thedetent cam here prevents the signal from passing only a switch 224 Thispermits setting the actuating or notched 1 portions of the cams veryclose together for closetiming without creating problems in cam contour,follower incrtia, and so forth. The cams are of a structure permittinginterchangeability, base of assembly, and hence are suitable for massproduction.

Although a specific example has been given wherein one selected peak isexcluded, it should be obvious that v the instant device can be adjustedto record all peaks. Also, in the example given, a column has been usedthat has a constant flow of carrier gas therethrough, thus notnecessitating use of a carrier gas valve. If desired, of course, such avalve may be employed. Moreover, although a device has been disclosedwherein one element (202) operates responsive to the force of gravity,it is permissible to modify the design to permit this element to beurged by other means, e.'g., under the bias of a spring.

The instant switch provides a fireproof-or explosion proof structure andis safe for use in hazardous locations. Although demonstrated by way ofexample to be suitable for use with chromatographic analyzers the use ofthis switch is not limited thereto but is suitable for use in any placewhere a programming switch of high speed with explosion proofcharacteristics and adjustability is desired. By the unique arrangementof multiple switches (best seen in FIGURE 7) a simultaneous actuation ofa plurality of circuits can be achieved with only one cam and levergroup.

I claim as my invention:

1. A timing switch comprising a first shaft, a first lever pivotallymounted by its central portion on said first shaft, a first cam followersurface disposed on one end of said first lever, a magnet disposed onthe opposite end of said first lever, a second lever having a second camfollower surface thereon, said second lever being pivotally mounted onsaid shaft thereby to dispose said second cam follower surface on theopposite side of the shaft from said first carnfollower surface, a pinprojecting from said second lever to engage said first lever at a pointbetween said first shaft and said magnet, a spring engaging said secondlever and biasing it upwardly; a second shaft mounted above said firstshaft, first and second adjustable cams adjacent each other disposedalong said second shaft, said first and second adjustable cams engaging,respectively, said first and second cam follower surfaces; each of saidadjustable cams including a cam disc having a circular central openingconcentric with said second shaft, in-

for said second adjustable cam having holes therein through which saidthird shaft passes; said first mounting disc having a hole thereinthrough which said third shaft passes; a fourth shaft, a detent dischaving a discontinuous peripheral flange protruding fromone sidethereof, said detent disc being fixedly mounted on said fourth shaft; afinger protruding upwardly from the magnet end of said first lever, asurface on said finger for engaging said discontinuous peripheral flangeon said detent disc; a

bearing block in which one end of each of said second and fourth shaftsis rotatablymounted; a rotary motor connected to one end of said secondshaft; gears on said second and fourth shafts, said gears engaging eachother, and said fourth shaft gear being of larger diameter than saidsecond shaft gear.

2. A timing switch comprising a first shaft, a first cam discsurrounding a portion of said first shaft and having a circular openingtherethrough, internal gear teeth around the circumference of saidopening, a circular shoulder surrounding said opening, a second shaft, apinion mounted on said second shaft and meshing with said internal gearteeth, a mounting disc having a circular flange, a hole through saidmounting disc, said second shaft passing through and being rotatablysupported in said hole, said cam disc shoulder being surrounded by androtatably supported by said mounting disc flange, said mounting discbeing mounted on said first shaft, a second cam disc, a second mountingdisc, said second cam disc and mounting disc engaging each other in thesame manner as said first cam disc and mounting disc, said secondmounting disc being mounted on said first shaft, a first degree lever ofrigid material, a weight comprising a magnet disposed at one end of saidlever, a camfollower surface disposed at the other end of said lever, apin disposed to engage said lever at a point in the path of motion ofsaid lever, a spring urging said pin toward said lever, said camfollower surface engaging said first cam disc, said second cam discengaging means for preventing the movement of said pin toward said leveruntil a predetermined event has occurred.

3. The apparatus of claim 2 further including a magnetically responsiveswitch disposed for engagement with the field of said magnet when saidlever is engaged by said pin before said predetermined event occurs.

4. The apparatus of claim 2 further comprising means for permitting saidlever to drop only once in a preselected number of revolutions of saidfirst shaft.

5. The apparatus of claim 4 wherein said means comprises a shaft, acircular disc, a discontinuous flange on the circumference of said disc,a finger on the magnet end of said lever, a portion of said fingerprotruding therefrom and position for engagement with the internalportion of said flange.

6. A timing switch comprising 'a first shaft; a first rigid memberrotatably mounted on said shaft for arcuate motion thereabout; a magneton one end of said member; a cam follower surface on the other end ofsaid member; said shaft engaging said member at a central portion of thelatter; a second rigid member mounted adjacent said first rigid memberon said shaft and extending toward said magnet; a pin mounted on saidsecond member and protruding toward said first member to engage thelatter at a point in the path of motion thereof; a spring "biasing saidsecond member towards said first member; a camfollower surface on saidsecond member; a second shaft; first and second adjustable cams disposedalong said second shaft, each of said adjustable cam discs including acam disc having a circular opening therethrough, :an internal geardisposed within said opening, a circular shoulder surrounding saidopening, another shaft, a pinion mounted on said another shaft andmeshing with said internal gear, a mounting disc having a circularflange, a hole through said mounting disc, said another shaft passingthrough and being rotatab ly supported in said hole, said shoulder beingsurrounded by and rotatably supported by said flange, and said mountingdisc being supported on said second shaft; said first adjustable camengaging said first cam follower surface; and said second adjustable camengag ing said second cam follower surface on said second memher.

7. The apparatus of claim 6 further comprising a detent means thatincludes a fourth shaft; means for linking said fourth shaft to saidfirst shaft; a disc mounted on said fourth shaft; a discontinuous camsurface surrounding a 10 portion of said disc; a finger engaging saidcam surface; said finger being attached to the magnet end of said firstrigid member.

8. The apparatus of 7 further comprising means for mounting said fourthshaft for selective reciprocable movement longitudinally thereof and forrotary movement.

9. The combination comprising a chromatographic column; a sample cellconnected to said column; a Wheat stone bridge having one branchdisposed in said sample cell, a pair of output terminals on said bridge;means for indicating and recording in bar graph form selected signalsappearing at said output -,terminals that further com prise means forconnecting said output terminals to said means for indicating includingaplurality of parallelconnected attenuators each said attenuator havingan individual switch in series therewith, and a programmer for actuatingsaid individual switches in a predetermined sequence that comprises foreach said individual switch a first means for actuating said switch,second means for returning said first means to a non-actuating positionthereby deactuating the switch, third means for connecting said firstand second means to :a source of power, and fourth means to selectivelyadjust said first means with respect to said second and third means, achart motor connected to said means for indicating and recording, and adelay relay means actuated in response to said second means foractuating said chart motor.

10. A timing switch comprising a first shaft, a cam, means forsupporting said cam on said shaft and for rotating said cam with saidshaft, means for adjusting said cam by rotating it relative to saidshaft, a second cam, a second means for supporting said second cam onsaid first shaft and rotating it therewith, a fulcrum, means forpivoting a magnet about said fulcrum along an 'arcuate path responsiveto said first cam, means to engage said means for pivoting when thelatter is at a first terminal point of its arcuate path, means to biassaid means to engage toward the other terminal point of the arcuatepath, means responsive to said cam to actuate said means to bias, andmeans for permitting said magnet to pivot through its arcuate path onlyonce in a preselected number of revolutions of said shaft, said meansfor permitting comprising a shaft, a circular disc having adiscontinuous flange on its periphery, said disc being concentricallymounted on said shaft, a finger on said magnet hand of said means forpivoting, and a portion of said finger protruding therefrom in positionfor engaging the internal portion of said flange.

11. The combination comprising a chromatographic column; a sample cellconnected to said column; a Wheatstone bridge having one branch disposedin said sample cell; a pair of output terminals on said bridge; meansfor indicating and recording in bar graph form selected sig- H3115appearing at said output terminals; means for connecting said outputterminals to said means for indicating including a plurality ofparallel-connected attenuators, each said attenuator having anindividual switch in series therewith; and a programmer for actuatingsaid individual switches in a predetermined sequence comprising aswitchactuating member for each said switch; a pair of actuating devicesfor each said member, one device of each of said pairs actuating saidmember of a corresponding switch to cause said switch to close, a seconddevice of each of said pairs actuating said member to cause saidcorresponding switch to open independently of said first device,actuating device adjusting means for adjusting the angular position ofeach of said devices independently to vary the angular relationshipbetween said devices and between said devices and driving meanstherefor; a chart motor connected to said means for indicating andrecording; and a delay relay means actuated in response to said onedevice of each of said pairs to deenergize said chart motor and toenergize said chart motor for a predetermined period of time when eachof said switches is opened.

(References on following page) 11 References Cited in the file of thispatent 2,874,239

UNITED STATES PATENTS Miller Sopfn. 1]., 1,773,539 Miller Aug. 9, 1930 51,787,292 Townsend Dec. 30, 1930 1,989,723 Tumor Fab. 5, 1935 2,398,988Zieboflz Apr. 23, 1946 2,450,311 St-ronk Tot a1 Sept. 28, 1948 12 322,826,908 Skarswom' Mar. 18, 1958 10 2,861,469 Kintzing Nov. 25, 1958 12Doneit Feb. 17, 1959 Robinson -1 Mar. 3, 1959 Norem Sept. 15, 1959Constantine May 31, 1960 OTHER REFERENCES Text: Electrical EngineersHandbook, Ponder-Delmar, IV (Wiley Handbook Senies), third odibion 1936,pages

11. THE COMBINATION COMPRISING A CHROMATOGRAPHIC COLUMN; A SAMPLE CELLCONNECTED TO SAID COLUMN; A WHEATSTONE BRIDGE HAVING ONE BRANCH DISPOSEDIN SAID SAMPLE CELL; A PAIR OF OUTPUT TERMINALS ON SAID BRIDGE; MEANSFOR INDICATING AND RECORDING IN BAR GRAPH FORM SELECTED SIGNALSAPPEARING AT SAID OUTPUT TERMINALS; MEANS FOR CONNECTING SAID OUTPUTTERMINALS TO SAID MEANS FOR INDICATING INCLUDING A PLURALITY OFPARALLEL-CONNECTED ATTENUATORS, EACH SAID ATTENUATOR HAVING ANINDIVIDUAL SWITCH IN SERIES THEREWITH; AND A PROGRAMMER FOR ACTUATINGSAID INDIVIDUAL SWITCHES IN A PREDETERMINED SEQUENCE COMPRISING ASWITCHACTUATING MEMBER FOR EACH SAID SWITCH; A PAIR OF ACTUATING DEVICESFOR EACH SAID MEMBER, ONE DEVICE OF EACH OF SAID PAIRS ACTUATING SAIDMEMBER OF A CORRESPONDING SWITCH TO CAUSE SAID SWITCH TO CLOSE, A SECONDDEVICE OF EACH OF SAID PAIRS ACTUATING SAID MEMBER TO CAUSE SAIDCORRESPONDING SWITCH TO OPEN INDEPENDENTLY OF SAID FIRST DEVICE,ACTUATING DEVICE ADJUSTING MEANS FOR ADJUSTING THE ANGULAR POSITION OFEACH OF SAID DEVICES INDEPENDENTLY TO VARY THE ANGULAR RELATIONSHIPBETWEEN SAID DEVICES AND BETWEEN SAID DEVICES AND DRIVING MEANSTHEREFOR; A CHART MOTOR CONNECTED TO SAID MEANS FOR INDICATING ANDRECORDING; AND A DELAY RELAY MEANS ACTUATED IN RESPONSE TO SAID ONEDEVICE OF EACH OF SAID PAIRS TO DEENERGIZE SAID CHART MOTOR AND TOENERGIZE SAID CHART MOTOR FOR A PREDETERMINED PERIOD OF TIME WHEN EACHOF SAID SWITCHES IS OPENED.